Problem: Nutrition and diet are key contributors to a healthy lifestyle, to the prevention and treatment of chronic diseases, and to positive medical and surgical outcomes in acute care. Although many physicians believe that nutrition care is part of their role, there is a longstanding nutrition deficit in medical education which impacts physician effectiveness in managing their patients’ nutrition-related concerns. Many physicians do not feel confident or competent in providing nutrition education or care to their patients, and recommendations on addressing this issue in Canadian medical schools and residency programs remain unclear. This study explored residents’ and preceptors’ perceptions and experiences of the family medicine (FM) and internal medicine (IM) residency programs at the University of Calgary to better understand the program’s barriers to nutrition education and nutrition care.Methods: Realist inquiry was used as a methodological framework, and a combination of realist inquiry and constructivist grounded theory techniques were used to collect, analyze, and synthesize data. Morphogenesis was used as a sensitizing concept to explain the findings of this study. Semi-structured interviews were conducted with FM and IM preceptors (n=11) and residents (n=9) to explore their attitudes, perceptions, and experiences with nutrition at the University of Calgary in 2020. Results & Conclusions: Participants believed nutrition care was relevant to their clinical practices, yet most were unequipped to address nutrition concerns. Confidence was a key mechanism that influenced the participants’ attitudes and behaviours around nutrition and shaped the overall presence and priority of nutrition in participants’ education and practices. Most participants reported low internal confidence in their nutrition knowledge which seemed to stem from a lack of education. Additionally, participants expressed a desire for clarity around their role in nutrition care. Other factors that influenced confidence included perceived culture, need, reward and perceived competence, which were reinforced by the settings that participants were exposed to. The interplay between these factors ultimately shaped the pervasive low presence and low priority of nutrition within the FM and IM residency programs. An empirically derived program theory described the material conditions and network of mechanisms that shaped the presence and priority of nutrition in medicine.